1. Field of the Invention
The invention relates to a method and a computer program for controlling the heat treatment of metal workpieces for industrial furnace plants, in order to provide conditions for increasing the degree of automation of the loading of furnaces.
2. Description of the Related Art
For the optimal technological preparation of the heat treatment of metal workpieces to be performed in batches for industrial furnace plants, methods are known which are to rationalize the sequences. So-called batch thermoelements are used, which are to ensure complete heating through of a batch by comparison of the exterior/interior batch temperature. In this subprocess, the program segment durations are dynamically lengthened until both measured temperatures are equal. Program segment durations are defined by one skilled in the art as the times for the heat treatment of the workpiece in the particular treatment section, these program segment durations representing a part of values for technological heat treatment formulas.
The attachment of the described batch thermoelements is performed manually in each new batch and obstructs a desired continuous and automated sequence of the heat treatment.
EP 0 556 176 B2 (DE 691 04 377 T3) discloses a special control system for the planning of the workpiece treatment in a heat treatment method for a plurality of connected chambers of an industrial furnace plant. The processing chambers process at least two parts simultaneously using unique processing times. This control system also has storage means for recording specific processing times for each part. The method only generally teaches time planning in a continuous furnace structure having the steps of storing and recording the functions of the control system, but not in connection with batch thermoelements, which are to ensure complete heating through of a batch by comparison of the external/internal batch temperature.
A method and computer program for the automatic preparation of technological formulas for the heat treatment of metal workpieces in industrial furnaces has already been sought internally. Through a program-controlled determination, it is to be made possible that the performance of heat treatments of metal workpieces in industrial furnaces can be planned better before the beginning of the heat treatment in the particular industrial furnace. The goal was to increase the degree of automation.
For this purpose, it was proposed according to PCT/DE 2008/001454, in a method and computer program, using                values for a material of a particular workpiece, details on heat treatment methods, and technical details of the particular industrial furnace,        a step-by-step specification or generation of parameters which can be precalculated for the heat treatment of the workpiece, and        a computer, which generates a heat treatment program, having databanks and a programmed storage of a generated heat treatment program and the retrieval for activation of the heat treatment in the industrial furnace            1. in a first program step, to select a material group and the material and to determine a heat treatment method as a function of the selected material,    2. in a second program step,            to input a wall thickness,        to select a comparative geometry,        to input a batch weight, and        to select a batch layout,as data of the workpiece/the batch, in order to calculate a virtual wall thickness automatically therefrom,            3. in a third program step, to integrate heating and quenching characteristics, which are a function of the material and are optionally manually changeable from the virtual wall thickness together with the data of the batch and the available parameters of the industrial furnace, and    4. in a fourth program step, firstly            to load data of the selected material on treatment parameters and data of the selected heat treatment method into a formula structure template and        to compile it into a formula structure from the formula structure template employing the data from a user interface, such as                    heating characteristic and            quenching characteristic and, if necessary,            a target hardness                        from which        values of formula segments, such as                    segment durations, which will be discussed in greater detail in the further description of the invention,            temperatures,            ramp slopes and/or temperature ramps, and            pressures                        are to be established and then, as a result of the fourth program step, a technological heat treatment formula is to be generated automatically, which can be reworked, stored in a program databank, and retrieved at the industrial furnace for the heat treatment of metal workpieces.        
The method and program can be expanded in a fifth program step, in that a transmission of the heat treatment formula to the furnace occurs. For this purpose, for the heat treatment of the workpiece/the batch running autonomously in the industrial furnace, the heat treatment program is retrieved from the program databank and mediated for the heat treatment in the industrial furnace. Accordingly, in this program databank, heat treatment programs have already been prepared and stored in the program databank.
The heat treatment method/program sequences contained in this program databank may be applied more rationally in regard to the required installation and function of the described batch thermoelements.
The installation of the batch thermoelements and the comparison of the exterior/interior batch temperatures resulting therefrom is a significant effort in general in heat treatment methods according to the species as a subprocess, because the program segment duration must be dynamically lengthened until both measured temperatures are equal.